Process and apparatus for producing hexamethylenetetramine and ammonium chloride



May 31,1927. c a CARTE-R 1,630,182l

PROCESS AND APPARATUS FOR PRODUCING HEXAMETHYLENETETRAMINE AND AMMONIUM GHLORIDE Filed July 30. 197:26 2 Sheets-Sheet l @m2722577 yar/agi 62271767, f/k l.

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.A .R T E T E N m v.. H m m H G N I C U D w P. R 0 F s U m P `v.. A s s E C 0 R P C. B. CARTER May 31, 1927.

AND AMMONIUM CHLORIDE 2 Sheets-Sheet 2 Filed July 30. 1926 Patented May 31, 1927.

UNITED STATES PATENT OFFICE.

CARNIE B. CARTER, DECEASED, ILATE OF PITTSBURGH, PENNSYLVANIA; BY MYRTICE G. CARTER, EXECUTRIX, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO S. KAR- PEN & BROS., OF CHICAGO, ILLINOIS, A CORPORATION F WEST VIRGINIA.

PROCESS AND APPARATUS FOR PRODUCING HEXAMETHYLENETETRAMINE AND AII- MONIUM CHLORIDE.

Application led July 30,

This invention relates particularly to the production of hexamethylenetetramine and ammonium chloride, and involves, as an important feature, a novel method of effecting separation of hexamethylenetetramil;e from i ammonium chloride. v

The primary object is to provide an economical method of producing hexamethylenetetramine and ammonium chloride and effecting separation thereof; and, further, to provide apparatus especially suited to the practice of such process.

A mixture of hexamethylenetetramine and. ammonium chloride, in certain proporf' tions, results from a reaction between methylene chloride and ammonia'. These compounds' may be produced by reaction between methylene chloride and liquid ammonia, or by reaction between methylene chloride and aqueous ammonia. Such reaction may be carried out under pressure, or in a closed chamber. The reaction may be expedited by means vof heat, practical working temperatures ranging from about 60 C. to

' about 130 C. The reaction is greatly expedited by employing a large excess of ammo-l nia, preferably 300 to 400% excess. Where such excess ammonia is employed, the reac-` tion preferably is performed at a temperature of about 100 C. in an autoclave, the pressure developed under such conditions being not excessive and the reaction being completed within a-period of a few hours.

It is preferred to form the hexamethylenetetramine and ammonium chloride by reacting upon methylene chloride with aqueous ammonia, employing a large excess of ammonia to expedite the reaction and enable it to be carried out within a comparatively short period, avoiding excessive pressures. Regardless of the manner in which the mixture of these salts is produced, the separation thereof may be economically effected in accordance with the invention herein described, which avoids the use of expensive solvents, and which also avoids the expense of evaporating large quantities of water.

Both hexamethylenetetramine and ammo- 1926. Serial No. 125,958.

nium chloride ossess great solubility in wa ter, as' has long een known; and the presence of either salt in the Water solution does not greatly aii'ect its solvent power for the other.

In the present invention, certain discoveries' of the inventor are utilized in a highly advantageous manner. Thus, hexamethylenetetramine has a very low solubility in water highly surcharged with ammonia gas. As much as 90% of the hexamethylenetetramine contained in a saturated aqueous solution, regardless of the presence of ammonium chloride in the solution, can be salted out in highly pure crystalline form by surcharging the solution with ammonia. On the other hand, the ammonia does not decrease the solubility with respect-to ammonium chloride, but increases such solubility to some extent. Again, methylene chloride reacts readily with ammonia in an Iaqueous olution which is saturated with respect to oth ammonium chloride and hexamethylenetetramine. In such reaction, carried on at elevated temperature, ammonia is consumed and the freshly formed ammonium chloride and hexamethylenet'etramine pass into solution. The ammonium chloride and hexamethylenetetramine thus formed in ucl saturated solution may be precipitated y ammonia, that is, lby restoring in the liquor J the ammonia consumed in the reaction.

In inventors application Serial No. 691,673, filed February 9, 1924, is described the manufacture of hexamethylenetetramine from methylene chloride and aqueous ammonia. The present invention is in the nature ooling and surcharging the liquor with of a modification of the invention described in said application, introducing improved methods of effect-ing separation of the products.

Apparatus especially well adapted for the practice of the present process is illustrated in the accompanying drawings, in which- Fig. 1 represents. a flowsheet showing diagrammatically the improved' apparatus for producing hexamethylenetetramine `nd ammonium chloride from methylene chloridev and aqueous ammonia, the apparatus includparatus shown in Fig. 1 lis also an ammonia recovery. plant, en-

in the process of producin fresh hexamethylenetetramine in cases w ere it is not desired to/ use the ammonium chloride for other purposes; and Fig. 2 illustrates diaammatically leaching apparatus suitable or use at F and/or I 1n the plant diagrammatically illustrated in Fi 1.

Referring to Fig. 1, A esignates a storage-tank for methylene chloride; B, an autoclave; C, an ammonia storage-tank, preferably for liquid ammonia; D, a stock-liquor storage-tank which in the preferred process contains lwater saturated with hexamethylenetetramine, and with ammonium, ch

ride, and with ammonia; E, a cooler and saturator adapted to receive the entire charge from the autoclave after the reaction has been completed; F, leaching system No. 1V comprising preferably the apparatus shown in Fig. 2, the hexamethylenetetramine being leached from the ammonium chloride4 in leaching system y which receivesV the filtrate from leachlng system No. 1 and in which the hexamethylenetetramine is precipitated by surcharging the filtrate thereinA with ammonia; H, an ammonia recovery plant in which the ammonium chloride recovered. from leaching system LNo. 1 may be treated, as for example, with milk of lime,the recovered ammonia being conveyed to tank C; I, leaching system No. 2 which may comprise apparatus of the kind shown in4 F1g.v2, the recipitated hexamethylenetetramine from being here subjected lto leaching withv .water charged with ammonia to remove the ammonium chloride remainin in the wet/ting solution of the precipitate hexamethylenetetramne from the precipitator G; J, a drier for the purified hexamethylenetetramine received from leaching system No. 2, the ammonia and water vapor evaporated Vat J being conveyed to a still K, and the dried hexamethylenetetramine being conveyed to the hexamethylenetetramine storage-ta L.; and M, a storage-tank for calciumchloride received from the vammonia. .recovery plantl H, assumirg the ammonium chloride to be treated at with milk of lime.

' The routing of materials through the apindicated in the main by lines and arrows, as follows: line albetween the methylene chloride tank A- and autoclave; lin'e b between the stockliquor tank D and the autoclave; line c between the ammonia tank C and the autoclave; line d between the autoclave an the cogle and saturator E; -linese and ,f betweeiithe ammoniav and saturator E; line g between the cooler and saturator .E and the stock-liquor tank D; ine h between the cooler and saturator E and the leaching 'system F; lines and j plant; line Z No.' 1; G, a precipitatora temperature of about d ride, the filtrate,

tank C and the cooler from leaching system F `to line g; line k from the line to the ammonia recovery from leaching system F to pref cipitatoi` G; line m from the line e of the ammonia tank C to precipitator G; line n from the precipitator G to leaching system 1; line o from leaching system I to hexamethylenetetramine drier J; line p from leaching system I to still K; line g from still K to precipitator G; line rs from hexamethylenetetramine dre'r J to storagetank L; line t from line fr-s to lines p and u; line u leading to line g; line 'v from still K to line u; and line w from still K to line d.

-In the preferred practice of the process, the autoclave B receives a charge of-autoclave liquor vfrom the stock-liquor tank D,

-this liquor being water substantially saturated, under atmospheric conditions of temperature and pressure, with hexamethylenetetramine and with ammonium chloride and strongly charged with ammonia. The desired charge of methylene vchloride from "tank A is also introduced into the autoclave, and ammonia from C is introduced, if necessary, preferably in suflicient quantity to bring`the ammonia concentration up to an excess of 300% to 400% above the ammonia required theoretically to react with the charge of methylene chloride introduced I into the autoclave. Heat is applied to the autoclave and continued for a period of from five to ten hours, or longer, depending upon the temperature employed and the ammonia concentration in the reacting liquor. In an event, the heating is continued long enoug to complete the reaction. Preferabl When the reaction is complete, the entire autoclave charge is transferred to the cooler` and saturator E, Where it is agitated and C. is employe cooled and treated with ammonia from C, v A

that is, ammonia is introduced into the container E until the ammonia contentreaches the same 'value as it possessed before reaction in the autoclave. The 'charge then the l is allowed to stand quietly untilthe ammonium chloride and hexamethylenetetramine produced in the reaction settle, and then most ofy the clear supernatant liquor is transferred through the pipe g liquor tank D. The remainder of the liquor, together with the precipitated ammonium chloride and hexamethylenetetramine, passes through line h to the first leaching system designatedF, Where the 4hexamethylenetet- -Iamine is leached from the ammonium chlosaturated with ammonium chloride and 'substantially saturated with hexamethylenetetramine being then passed .to the precipitator G.

It may be'mentioned here that it is important to introduce into the` cooler and saturator E just sucient ammonia to bring,

to the stockthe solutionto the same ammonia concentra.`

ficient ammonia is introduced at E, more ammonium chloride and less hexamethylenetetramine will be precipitated than was produced in the reaction. On the other hand, if

,. too much .ammonia 1s used at this point,

. leaching apparatus 5F.

more hexamethylenetetramine and less ammonium chloride than was produced in the reaction will be precipitatedf To keep the system properlyT balanced, substantially the correct amount of vammonia lshould be introduced at E.

The apparatus. shown in Fig. '2 is available for each leaching system F andI, itpbeingA observed,however, that the leaching apparatu's I need not be of as large capacity as the Referrin to Fig. 2, A', B', C', D and E designate ter-tanks having false' bottoms supporting filter-cloths; F designates asimilar filter-tank; and G', HV I, J and K designate filtering-fluid tanks.

Each filter-tank is of receive an entire charge of the preci itated ammonium chloridel and hexamet ylene-v tetramine from the cooler and saturator E. The filter-tank E may be assumed to be l filled about two-thirds full ofthe 'mixturel of from the cooler and satu-r 'filtering operation which said salts received rator. Before the will be presently described, the mother liquor is withdrawn by suction from the filter-tank A', yleaving the mixture of salts wetted,how with the mother liquor. The filtering fluid in ythe tank G at the beginning'of a filtering operation isprcferably pure water; that in the tank H 1s the filtrate received from the tank G after a `preceding ltering operation performed. in thefilter-tank A; that vin the tank I l from the tank H after a filtering operation in the tank-B',

and so on throughout the series. That is, the filtrate from any lter- -tank of the series is employed as a filtering iuid for the next filter-t k of the series in the next cycle of operations. The 'filter-tank F may be assumed to have passed through the cycle of filtering operations from right to left in the diagram shown in Fig. Q1, to have been taken'ultimately from thef'position of the tank A', wherelitj containe only ammonium chloride wetted with a liquor containing. a'negligib amount of hexamethylenetetramme in solution, to have been emptied, the ammonium chloride being sent to the ammoniarecoveryplant H ofFi-g. 1, and finally ceive a fresh charge of hexamethylenetetramltents sent filtering-Huid tanks,

.with a valve 16a,

sufficient capacity to .throu h the is the filtrate received` tank A being quite to be standing by readyto re ine and ammonium chloride salts from the cooler and saturator E, after which the filtertanks will be shifted one step to the left in Fig. 2, the tank F entering the rogression` in the place of the tank E- and t e tank A being taken out of the series to have its conto the ammonia recovery plant. In Fig. 2, 1, 2, 3, 4 and 5 designate pipes connecting the lower ends of the lfilter-tanks with the upper ends of the corresponding these pipes being` equipped with unions l, 2, 3, 4 and 5; 6', 7, 8, 9-and 1() designate pipes connecting the bottonis of filtering-Huid tanks with the l upper portions of the filter-tanks, these pipes being equipped with valves 6, 7a, etc., and with unions 6", 7", etc., and also equipped with pumps 6, 7, etc.; 11, 12', 13 and V14: designate pipes onnecting pipe 6 with pipe 2,"pipe 7 with pipe 3, etc.; 15 designates'a pipe leadin from pipe l0 and by means o1' which the nal filtrate may be ,conveyedI to the precipitator G shown in Fig. 1, the pipes being equipped with valves 11a-15a; 16 designates a pipe communicating with the upper portion of the tank G andequipped the pipe leadingto -an exhaust pipe 20 with which may be connected -a vacuum pump (not shown) and 17, 18 and 19 designate pipes connecting the upper por- -tions of the `tanks H, I and J with the suction line 20, it being noted that suction line 20 is also connected withthe upper portion of the tank K. The pipes 17-19 are equipped with valves 17 a--193 and the pipe 20 is equipped with a valve 20a. 1

If we' assume that at the beginning of a ilterin operation involving all of the .apparatus s own in Fig. 2,v F', the tank E is about two-thirds filled with a mixture of hexamethylenetetramine and ammonium chloride, wetted with mother liquor, to the filter-tank E',

lines 5' and 20, and if we assume that t e wetting fluid in the tank A is about lone-fourth of the leaching fluid (water) in thetank G', the lter-tanks A Bv', C', and

excepting the tank` which remains afterl applying suction which may be done ramine andl ammonium chloride in solution,

the amount of hexamethylenetetramine 1n thel small, that in the tank' that in the tank C lstill larger, and that' in the tank D still larger than that in the tank C. This will be the situation after the systemhasreached a balanced condition, assuming ing treated are in the propor ion in which they are formed by vreacting' upon methylene chloride with ammonia, the amount of ammonium chloride produced in such reaction is several times as large the hexamethylenetetramine produced.

has been found B -being larger,

It by experiment that approxi'.-

it being noted thatA th the salts be-v vation on the basis.

mately '80% of the mother liquor can be removed fromthe salt mass by suction on a filter. -Where this is true, t'he use of five -lter-tanks in the Aleaching system is sulfi-` cient to accomplish the desired result. Were f enetetramine (in the salt-wetting solution) originally present .in thesalt mixture; tank B contalns ammonium chloride and approximately 1.5% of thevoriginal hexamethylenetetramine; tank C contains ammonium chloride and approximately 6.2% of the orlginal hexamethylenetetramine; and tank D contains ammonium chloride andapproxilnately tetramine. fresh charge of ammonium-chloride and hexamethylenetetramine from the cooler-saturator E' of Fig. 1. The leaching fluid tank G contains pure water; and the leaching 'mediate concentration values.

fiuid tanks H', I',` J and K' contain saturated solutions of ammonium chloride, these solutions being partly saturated (in successively increasing strengths) with hexamethylenetetramine, the solution in H having a very low hexamethylenetetramine concentration and the solution in K having a verymuch higher hexamethylene'tetramine concentration, with I and J having intering operation, the fluid water) in tank G is circulated through the ter-tank A', where it becomes saturated with ammonium chloride and, at the sa'me time, dilutes the wettin liquor of the ammonium chloride in ta A', until the amount of hexamethylenetetramine remainingin solution inthe tank A becomes ractically few hundredlths of 1%. tion in tank H', resulting from a former leaching operation in the predecessor of the tankA, is saturated with ammonium chloride, land hence will not take u ammonium chloride from the tank B. imilarly, the leaching fluids Vof the tanks I', J and K will` not take u ammonium chloride from the lilter-tanks ','D and E. On the other hand, the leachingiiuidsA of the successive leaching tanks will become successivel stronger in hexamethyleneltetramine; and, fin leaching iuid of the tank K' will take u from the tank E' approximately 75% of the hexamethylenetetramine therein.

As has been stated, the filtrate in the tank K', at the end of the filtering operation, passes ythrough the vpipe 15 `(corresponding with the pipe L of Fig. 1) to the precipitator .of the original hexamcthylen" Tank E', as stated, contains .a

In the leachinsignificantv onlyr a The leachiiig solually, the" hexamethylenetetramine passes from the precipitator G to the second leaching system designated I; This may be similar inl all respects to the `leachingsystem shown in Fig. 2, except that the apparatus may be smaller. In the second leac ing system, the

tank E contains a charge of hexamethylenefeti-amine received from the precipitatr G, v

this hexamethylenetetramine being wetted vwith water saturated with ammoniulnchloride and hexamethylenetetramine. f The purpose ofthe second leachingss'ystem is to take nlehylenetetramine. This preferably is accomplished by passing successive char es of hexamethylenetetramine contained in t e filter-tanks through the filter system from right to left in the diagram shown in Fig. 2. In this case, however, the filtering iiuid in the tankG' preferablyr is water strongly charged with'ammonia. The ammonia tends to prevent the l1examethylenetetramine from going into solution and also increases the solubility for ammonium chloride. Bypassing the filter-tanks containing the hexamethylenetetramine charges in Isuccession through the filter system from right to left, and performing the filtering operations through the several filter-tanks in the manner stated above, the effect is to remove from the hexamethylenetetramine in each charge practically all of the ammonium chloride which is present in the wettino` That is, this 'result is accomplished by the time the charge has progressed to t eposition of the tank A andbeen subjec ed in that position to a washing operation with water surcharged with ammonia. At the end of the filtering operation, the filtrate from each of the filtering-Iiuidtanks is pumped -into the next succeeding filtering tank, the final filtrate from the tank K', however, passin to the still K. .The filter-tanks are then a vanced one step to the' left, a fresh charge taking the place of the tank E. It will be noted, for example, that the filtrate from the tank G can be pumped therefrom bythe pump'cl'through the ylines 6, 11a-and ,2, to the tank H', In an analogous manner,

the filtrate from each of thelilter-tanks can i succeeding tank,after.

vbe emptied into the the lat-ter has been emptied.

It may be added that by leaching hexaout the ammonium chloride from the mother liquor which wets the precipitated hexa' liquid methylenetetramine in the manner described,

. practically all' of the ammonium chloride may be removed therefrom, only a few thousandthsof 1% remaining in the hexamethyltetramine in solution in successively increasenetetramine. The hexamethylenetetramine` ing amounts.

loss 1s insignificant. Also, it may be stated 3. I n effecting the separation of hexathat after the removal of the tank A from methylenetetraniine from ammonium chlothe firstleaching system, the tank then conride, the steps comprising leaching with liq- 70 taining substantially pure ammonium chlolu'or, saturated with respect to ammonium ride with only a small amount of liexamethchloride, ammonium chloride inv solid form yleiietetramine remaining in the wetting and hexamethylenetetramine insolution in fluid, water may be passed through the tank successively increasing amounts, and pass-- of ammonium chloride until all of the aming the final filtrate as a leaching fluid 75 monium chloride is put into solution, and through a charge comprising ammonium this solution may be pumped to the ammonia chloride and hexamethylenetetramine in recovery plant H of Fig. 1. solid form.

It will be understood that whenthe leach- 4. The .process which comprises: forming inw system yl? is first putafinto op.eration,=the hexamethylenetetramine and ammonium. 90

D filter-tanks of the system may initially conchloride from methylene chloride and am- -tain charges of salts from the cooler and monia; leaching successive charges of the saturator E, and that filtering operations Amixture of salts thus produced in a series of may be carried on until the filtering system containers containing relatively large 2 reaches a balance with graduated percentamounts of ammonium chloride and succes- 85 ages of hexamethylenetetramine in the wetsively increasing amounts of hexamethylting water of the ammonium chloride reenetetramine in solution, as a wetting fluid, maining in the filter-tanks; or any desired the original leaching fluid being saturated expedient may be resorted to at the outset with respect to ammonium chloride from the to bring the charges in the filter-tanks into charge containing the least hexamethylene- 9 proper condition to enable the process to tetramine, the filtrate from each charge bework smoothly thereafter.4 ing employed as a filtering fluid for the next The process described is adapted to the succeeding charge; and leaching a fresh production of practically pure hexameth lcharge of hexamethylenetetramine 'and am- 3 enetetramine on a large scale, the plant bemonium chloride with the filtrate from the ing of any desired capacit within practical next preceding charge in the series. limits. `The process operates smoothly and 5. The process which comprises: forming the system can be readily maintained in balhexarnethylenetetramine and ammonium anced condition. chloride by reaction between methylene- Whilst hexamethylenetetramine is a base chloride and aqueous ammonia in a liquor 10 'and not a salt in the strict sense, it is substantially saturated with hexamethyleneoften spoken of as a Salt and is referred to tetramine and ammonium chloride, in the in this manner, for convenience, in the specipresence of an excess oi ammonia; intro ucfication and claims. Also, the term leaching ammonia into the reaction liquor and re- 40 ing is conveniently employed in the specistoring the liquor substantially to the con- 105 fication and claims to denote the operation eentration existing previous to the reaction of passing a solvent or washing fluid through and precipitating the salts formed in the a mixture of solid compounds, or through a reaction; separating the clear liquor. from compound, for the purpose of effecting the the precipitated salts; subjecting successive vdesired separation. charges of the salts to serial leaching, the fil- 110 The foregoing detailed description4 has trate from each charge being saturated with been given for clcarness of understanding f ammonium chloride and being employed to only, but no unnecessary limita-tions should leach the next succeeding charge, the last be understood therefrom, but the appended charge in 'the series being a mixture of hexaclaims should be construed as broadly as permethylenetetramine and ammonium chloride 115 missible, in view of the'prior arti'j substantially in the-proportions formed, but What is claimed is: wetted with a solution of both salts; and 1. In effecting the separation of hexasurcharging the final filtrate with ammonia methylenetetramine from ammonium chloand thus precipitating a ma]or portion o 12o ride. the step which comprises: leaching with the hexamethylenetetramme. liquor saturated with respect to ammonium 6. The process which comprises: forming chloride a series of charges comprising amhexamethylenetetramine and ammonium monium chloride and hexamethylenetetramchloride by reaction between'methylene chloine. ride and aqueous ammonia in a liquor sub- 2. In effecting the separation of hexastantially saturated with hexamethylenetet- 125 methylene'tetramine from ammonium chloramine and ammonium chloride, inthe pres-v ride, the step which comprisesdeachng with ence of an excess of ammonia; introducing liquor saturated with ammonium chloride a ammonia into the reaction liquor and restorseres of charges comprising ammonium ing the liquor substantially to 'the concentrachloride in solid form and hexainethylena tion existing previous to the reaction and la precipitating the salts formed Ain the reaction; separating the clear liquor from lthe precipitated salts; subjecting successive charges ofizthe salts to serial leaching, the filtrate from each charge being saturated with ammonium chloride and being employed to leach the next succeeding charge, the last charge in the series being a mixture of hexamethylenetetramiyne and ammonium chloride substantially 1n the proportions formed,-but wetted with a solutlon of both salts; surcharging the final filtrate with ammonia and thus precipitating'a major portion of the hexamethylenetetramjne; and leaching the precipitated hexamethylenetetramine with a liquor comprising ammonia.

7. The process which comprises: forming hexamethylenetetramine and ammonium chloride by reactionV between methylene chloride and aqueousv ammonia in a liquor substantially saturated with hexamethylenetetramine and ammonium chloride, in the presence of an excess of ammonia; introduc- 1ng ammonia into the reaction liquor and restoring the liquor substantially to the concentration existing previous to the reaction and precipitating the salts formed in the reactlon; separating the clear liquor from the precipitated salts; subjecting successive charges of the salts to serial leaching, the filtrate from each charge bein saturated with ammonium chloride an being employed to leach the charge, the last charge in .the series being a mixture of hexamethylenetetramine and ammomum d, but wetted with a solution of both salts; surcharging the lnal filtrate with vchloride substantially in ammonia and thus precipitating a major portlpn of the hexamethylenetetramine; and leaching the precipitated hexamethylenetetrammewith water strongly charged with ammoma.

8. The process which comprises: form-` mg h examethylenctetramine and ammonium chloride by reaction between methylene chloride and aqueous ammonia in a liquor substantially saturated with hexamethylenetetramme and ammonium chloride, in the presence of an excess of ammonia; introduclng ammonla into the reaction liquor and restoring the liquor substantially to the concentratlon existing previous to the reaction and precipitating the salts formed in the re-` actlon; separating the clear liquor from the precipitated salts; subjecting successive charges of the salts to serial leaching, the ltrate from each charge being saturated with ammonium chloride and bein employed to leach the next succeeding c arge, the last charge in the series being a mixture of hexamethylenetetramine and ammonium the proportions wetted with a solution of both arging the4 final filtrate with formed, but salts; surch next succeeding chloride substantially in the propor,. tions forme ammonia and thus precipitating a major portion of the hexamethylenetetraminev; leaching the precipitated hexamethylenetetramine with water strongly charged with ammonia; t and drying the hexamethylenetetramine and freeing it from ammonia. l

9. The process which comprises: forming hexamethylenetetramine andy ammonium chloride by reaction between methylene chloride and aqueous ammonia in a liquor substantially saturated with hexamethylenetetramine and ammonium chloride, in the presence of an excess of ammonia; introducing ammonia into the reaction liquor and restoring the liquor substantially to the concentration existing previous to the. reaction and precipitating the salts formed in the reaction; separating the clear liquor from the precipitated salts; subjecting successive charges of the salts to serial leaching, the filtrate from each charge lbeing ysaturated with ammonium chloride v and `being employed to leach the next succeeding charge, e last charge in the series being a mixture of hexamethylenetetramine and ammonium oride substantially in the proportions formed, but wetted with a solution of both salts; surcharging the final filtrate with ammonia and thus precipitating a major portion of the hexamethylenetetramine; and leaching the precipitated hexamethylenetetramine with water stron ly charged with ammonia, the leaching Huit? passing serially through a series of charges of hexamethylenetetramine containing successively more and more ammonium chloride in the wetting solution, the final charge in the series being hexamethylenetetramine as precipitated, wet with the mother liquor in which precipitation occurred.

10. The process which comprises: forming hexamethylenetetramine and ammonium chloride by reaction between methylene chloride and aqueous ammonia in a liquor substantially saturated with hexamethylenc- 11o tetramine and ammonium chloride, in the presence of an excess of ammonia; introducing ammoniaJ into the reaction liquor and restoring the liquor substantially to the concentrationy existlng previous to the reaction wand precipitating the salts formed in the re- Y action; separating the clear liquor from the precipitated salts; subjecting successive charges of the salts to serial leaching, the filtrate from each charge being saturated with ammoniumchloride and being em'- ployed to leach the next succeeding charge, the last charge in the series being a mixture of hexamethylenetetramine and ammonium chloride substantially in the proportions formed, but wetted witha solution of both salts; surcharging the final filtrate with ammonia and thus precipitating almajor portion of the hexamethylenetetramine; leaching the precipitated ,hexamethylenetetramine 4 130 ammonium chloride in with Water strongly charged with ammonia,

containing successively more and more the wettlng solution,

the final charge in the series being hexamethylenetetramine as precipitated, Wet with the mother liquor in which precipitation occurred; and drying the charge of hexamethylenetetramme leached charges.

' MYRTICE G. CARTER, Emeeutm'w of the Estate of Oar/nie B. Garter,

Deceased.

first in the series of l" 

